You can sell a house in England when the unvented cylinder has no building control record — nothing in law blocks the sale. What you cannot do is hand over a certificate when the buyer's solicitor asks for one, so the gap has to be closed or explained. Two routes exist: a duplicate certificate from the installer's competent person scheme, or a regularisation certificate from the local authority under regulation 18 of the Building Regulations 2010. This page covers England. It sets out what each document proves, how far back a council can still act, and what a buyer's surveyor tends to raise about the cylinder itself.
Does selling a house with an unvented cylinder require a building regulations certificate?
No rule in England makes a building regulations certificate a condition of selling a house with an unvented cylinder. The sale itself is not blocked. The pressure comes from the buyer's side, because conveyancing enquiries ask for evidence that notifiable work was approved.
An unvented hot water cylinder is a sealed cylinder fed straight from the mains, with no cold tank in the loft. It is controlled work under Schedule 1, Requirement G3 of the Building Regulations 2010 in England. Installing or replacing a hot water system is notifiable work, and GOV.UK states the consequence plainly: without approval you will not have the certificates of compliance you may need when you want to sell your home.
Which document proves an unvented cylinder was signed off in England?
Three different papers turn up in a sale, and only two of them are building control records for an unvented cylinder.
- Competent person certificate — issued when the installer was registered in a scheme for this work. Schedule 3 of the Building Regulations 2010 lists installing a hot water system among self-certifiable work. GOV.UK states the owner receives the certificate within 30 days and the local authority is informed.
- Completion or regularisation certificate — issued by the local authority. It applies when the installer was not in a scheme, or when nobody notified the work at the time.
- Benchmark checklist — the manufacturer's commissioning and service record. Heatrae Sadia states it can be used to demonstrate compliance with Building Regulations and should be given to the customer. On its own it is not a local authority record.
Approved Document G expects the work to be done by someone competent for it, shown by scheme registration or a valid qualification card for unvented hot water systems. If you are unsure which document you are holding, see what an unvented cylinder certificate contains and who may install an unvented cylinder.
Competent person certificate or regularisation certificate: which one applies to your cylinder?
Two certificates can cover an unvented cylinder, and which one applies depends on whether the installer was registered in a competent person scheme at the time. The comparison below is for England.
| Criterion | Competent person certificate | Regularisation certificate |
|---|---|---|
| When it is issued | After installation, through the installer's scheme; GOV.UK states the owner receives it within 30 days | Later, by the local authority, on a written application from the owner under regulation 18 |
| Who starts it | The registered installer notifies the scheme; the owner applies for nothing | The owner applies for work that has already been carried out |
| What it states | The work was self-certified as compliant and the local authority was informed | Evidence, but not conclusive evidence, that the requirements were met |
| Inspection of the work | None: compliance rests on the registered installer's own certification | The authority may require the work to be opened up, tested or sampled |
| Work it covers | Work notified at the time of installation | Unauthorised work carried out on or after 11 November 1985 |
How does a regularisation application for an unvented cylinder work in England?
A regularisation certificate is applied for in writing to the local authority under regulation 18 of the Building Regulations 2010. It covers unauthorised building work carried out on or after 11 November 1985, which takes in an unvented cylinder that was never notified. The application needs a description of the work, so far as is reasonable a plan of it, and a plan of any further work needed to make it comply.
The authority may require the work to be opened up for inspection, or tests and samples to be taken. The requirements applied are those in force when the work was done, not today's version. Regulation 18 calls the certificate evidence, but not conclusive evidence, that those requirements were met. Nobody can therefore promise a buyer a particular result in advance.
The same route exists when a boiler was never notified, and the two often come up together in the same enquiry: regularisation for an unnotified boiler.
A missing certificate is a paperwork gap, not a reason the house cannot be sold. What a buyer cares about is whether the unvented cylinder meets Requirement G3 and whether a record exists. Both can be looked at before exchange: a duplicate from the scheme operator, or a regularisation application to the local authority under regulation 18.
How far back can a council act on an unvented cylinder fitted without notification?
A local authority in England can act on building work for up to ten years after it was carried out, and that includes an unvented cylinder installed without notification. Section 36 of the Building Act 1984 lets the authority serve a notice requiring work that does not comply to be removed or altered so that it does. If the notice is not followed within 28 days, the authority may carry out the work itself and recover the cost. There is a right of appeal to the magistrates' court.
The time limit in section 36(4) used to be twelve months. Section 38 of the Building Safety Act 2022 extended it to ten years, in force in England from 1 October 2023. GOV.UK also notes that work done without approval can lead to prosecution and a fine, and that the building control body may charge for putting matters right.
What does a buyer's surveyor look at on the unvented cylinder itself?
The discharge arrangement is usually the first thing a surveyor checks on an unvented cylinder. Approved Document G in England expects the safety valves to discharge through a short metal pipe into a tundish, an open funnel that makes a discharge visible. The tundish should be vertical, in the same room as the cylinder, as close as possible and below the safety device, with no more than 600 mm of pipe between the valve outlet and the tundish. The final discharge must end up somewhere it can be seen but causes no danger.
Requirement G3 also expects at least two independent safety devices in addition to the thermostat, so that the stored water cannot exceed 100 degrees Celsius. Heatrae Sadia requires an annual service by a competent person, logged in the Benchmark service record, and warranty cover can fall away without it.
Valves, the expansion vessel, the tundish and the discharge pipework are work for a qualified engineer, never a job for the seller. What you can safely check yourself is the boiler pressure gauge, the thermostat and programmer settings, the reset button and bleeding radiators.
What can you arrange before the house goes on the market?
Four steps are within your control as the seller of a house with an unvented cylinder and no building control record.
- Ask the scheme operator for a duplicate certificate. GOV.UK publishes the list of currently authorised competent person schemes.
- Ask the local authority building control team whether any record of the installation exists.
- Apply under regulation 18 for a regularisation certificate, if the work was carried out on or after 11 November 1985 and was never notified.
- Have a qualified engineer inspect the installation against Requirement G3 first, so you know what any application would have to cover.
FM Power is Gas Safe registered and works across London and the surrounding counties, seven days a week. If the cylinder needs work before a sale, our Megaflo and unvented cylinder work starts with a free home survey and a written fixed price.
Sources
- Approved Document G (with 2024 amendments), for use in England
- Building regulations approval: when you need approval — GOV.UK
- Building regulations approval: use a competent person scheme — GOV.UK
- Competent person scheme: current schemes and how schemes are authorised — GOV.UK
- The Building Regulations 2010, regulation 18 (regularisation certificates)
- The Building Regulations 2010, Schedule 3 (self-certification schemes)
- Building Act 1984, section 36
- Building Safety Act 2022, section 38
- Building Safety Act 2022 (Commencement No. 5) Regulations 2023
- Heatrae Sadia — Megaflo Eco SystemFit installation manual